Thermoplastic resins such as styrene-acrylonitrile copolymer resins, α-methylstyrene-acrylonitrile copolymer resins and styrene-acrylonitrile-phenylmaleimide copolymer resins are conventionally blended together with graft polymers obtained by graft polymerizing rubbery polymers with monomers providing compatibility with the resins. The resultant materials represented by ABS resins and ASA resins exhibit impact resistance and have widespread use. Of these materials, ASA resins involving such rubbery polymers as alkyl(meth)acrylate saturated rubbers characteristically exhibit good weather resistance.
On the other hand, ASA resins have drawbacks in that colored shaped articles have an unsatisfactory appearance due to reasons such as poor color production as well as exhibit low impact resistance. In order to improve the balance between poor appearance and impact resistance, ASA resins are proposed which involve, as components, acrylate ester rubbery polymers having a combination of rubber particles with different particle diameter distributions (Patent Literatures 1 to 3).
Further, in order to complement the defects of ASA resins, a thermoplastic resin composition is proposed which involves an ASA resin in combination with an AES resin including an ethylene-propylene rubber component (Patent Literature 4).
However, these thermoplastic resin compositions are unsatisfactory in any of impact resistance, rigidity, weather resistance and pigment coloring properties and cannot sufficiently meet the recent demanding needs.